With conventional road pavers, especially with asphalt road pavers, it is well known that the paving screed (abbreviated in the following to “screed”) must be guided in a floating manner over the material to be paved during the working process. Such screeds may be designed as rigid screeds or as screeds with sliding parts. Adapting the paving screed to the desired working width is effected by the optional mounting of suitable add-on screed elements and/or by retracting and extending movable screed segments with respect to a basic screed. The width of the screed has a decisive effect on the work processes of the road pavers, for example, on how quickly the paver can travel during the laying of a support layer of a road, how much electricity has to be produced by a generator for supplying electric loads on the screed and how much paving material has to be transported from the material bunkers of the road finisher to the screed. Since the width of the screed is variable, the current width of the screed must be entered by the operator at the road paver to control the workflow. The paving screed can be held in a desired position during the paving process by means of generally two hydraulic actuating cylinders, which are, for example, connected on the piston side or on the housing side with the chassis of the road paver and on the piston rod side with the paving screed or vice versa. For example, when the paver is stopped, the pressure on the screed is usually relieved by means of the hydraulic actuating cylinders in order to prevent the screed from sinking into the mixed material. It may also be necessary to lessen the load on the screed when the road paver ascends a hill, e.g., in order to increase the traction of the road paver. Such a road paver is known, for example, from EP 2 233 641 A2, to which reference is made herewith.
However, the problem here is that the operator of the road paver must enter the width of the screed manually in order to control the workflows at the road paver. In this case, it may occur that the precise width of the screed is not known exactly to the operator, particularly when width-adjustable screed segments are used. Thus, deviations of the set screed width from the actual screed width can occur. The consequence is longer warming-up times for screed heating systems, a failure to reach target temperatures, an increased strain on generators and electrical components of the heating system (for example, safeguards) and increased fuel consumption. In addition, the center of gravity of the screed is usually not known precisely and changes with altered paving widths. This makes it difficult to control or regulate the necessary load pressure or relief pressure to be applied to the screed by the hydraulic actuating cylinders accurately. However, in order to ensure a correct working of the road paver, a correct load or relief pressure on the screed is necessary, as otherwise the screed is subjected to asymmetric pressures, which adversely affects the compaction of the mixed material. The set pressure must therefore frequently be changed manually in order take the total weight of the screed into account adequately during the adjustment of the hydraulic cylinders.